Because, at peak revs of 11,000, the piston is reaching a peak deceleration of 4,500 G as it reaches TDC, and that bends and stretches the moving parts. According to my little scale, piston, ring, wrist pin, and wrist-pin bearing weigh 174 grams and the small end of the rod 72 grams, so the tension in the rod required to reverse their motion at TDC and 11,000 rpm was 2,700 pounds. The rod was stretching, the wrist pin bending, the piston’s wrist-pin bosses bending as well. In the top and bottom con-rod needle bearings, the cylindrical needles were flattening slightly at their line contacts with their races, which, in turn, were being elastically “dented” by that same force. Down below, the crankpin was being pulled upward, bending the crank. And the crank main bearings—one ball and one roller bearing—were likewise deflecting.